The invention relates generally to an electronic reprographic printing system, and more particularly concerns an apparatus capable of producing reprographic masters and for subsequent printing on copy sheets by employing previously produced masters in printing operations.
To date, the entry of electronic high quality, multicolor reprographic printing systems into the commercial printing market has been limited by factors relating to the quality of the image produced by these systems, the productivity of these systems and by the development and capital unit costs associated with this technology.
The commercial printing market has recently increasingly utilized computer technology, particularly in the field of color printing. However, this utilization has generally been limited to preparatory operations, such as text editing, composition, page make-up, plate or master making, and associated functions. The standard commercial printing processes themselves, principally letterpress offset lithography and gravure, are not readily computer compatible. Even the most advanced printing operations now available utilize computerized processes, based on digital technology, only up to the preparation of the film, or in some instances up to the preparation of the printing plates, masters, or cylinders. Beyond this stage in the process, these media are then used with traditional techniques and equipment to produce printed sheets.
This is, at least in part, due to the fact that computer compatible printing processes, such as electrophotography, ink-jet and thermography, cannot yet satisfy the normal image quality and productivity requirements of most segments of the commercial multicolor printing market. Thus, there is a need for an automated system capable of printing high quality images, at a sufficient rate, from information received either directly from a computer or scanned from existing images.
Recent developments have vastly improved the quality of the images produced by electronic reprographic systems. However, currently available systems have been unable to meet the productivity and reliability requirements of the commercial printing market.
There is thus a need for an electronic reprographic apparatus for rapidly and reliably producing multiple copies of high image quality.
The cost of equipment currently in use in the commercial printing market, letterpress, lithographic offset and gravure systems, is very high. The required capital investment cost has frequently been kept reasonably low by basing new equipment designs on modifications of existing devices. A prominent example of this is the offset press, early versions of which were developed through the conversion of older letterpress machines then in existence. A further factor is the retraining of skilled operators and service personnel. The cost of these is usually also reduced by introducing new technology by modification of existing designs.
Most standard sheet-fed offset press architectures are based on a sheet path low in the press structure and on feeding the imaging materials, i.e. ink and water, downward from above. In contrast, most electronic reprographic machines feature a high paper path, with the imaging material, i.e. toner, being fed upward from below. This basic structural difference is one major reason why electronic reprographic technology has not previously been combined with the mechanical structures available in lithographic offset and gravure systems.
Thus, there is a need for a reprographic printing apparatus of enhanced productivity which is capable of simultaneously printing and producing masters.